Netflix's Q4 subscriber growth beat the Street, passing 20 million subscribers for the first time, but revenue was a little weak.

Notably, Netflix is NOT providing full-year revenue or subscriber growth guidance, other than that it expects "domestic subscriber net additions to continue to grow in 2011."

This omission may surprise some people; Netflix says it's doing this because its business is "so dynamic."

Netflix finished Q4 with 20.01 million subscribers, more than the 19.5 million the Street was expecting. During 2010, it added 7.7 million subscribers, more than the 2.9 million subscribers it added in 2009.

Netflix continues to evolve the way it reports earnings: Instead of the standard press release like most companies issue, it posted a letter to investors in the form of a PDF file, including results and commentary. (It also doesn't host a traditional earnings call; it only does a Q&A, where questions must be submitted via email.)

(a) What will our domestic growth trajectory be over the coming years, given our strategy to maintain modest domestic operating margins so that we can invest aggressively in additional streaming content?